Optical pattern projection can be used in a variety of applications such as three-dimensional (3D) or depth mapping, area illumination, and LCD backlighting. 3D (or depth) mapping, for example, refers to a set of 3D coordinates representing the surface of an object. As part of the process of depth mapping, light (i.e., visible, infra-red, or other radiation) can be projected onto a region with a pattern of high quality (e.g., good resolution) and well-controlled intensity, so that depth values can be found reliably over a substantial part of an object or objects in a scene.
In some applications, diffraction gratings are used in creating a desired projection pattern. A diffraction grating can be implemented, for example, as an optical surface that is etched, molded or deposited on the surface of a substrate. In some systems, first and second diffraction gratings are arranged in series to diffract an input optical beam.